how do i update my ipad? i need iOS 5 to update iplayer and bbc iplayer etc but don't know how to do.

hello, currently trying to watch i player on my i pad 2, but says it needs updating. I usually just click update and it does it for me. However today it say i need to have iOS 5 software to do this. How do i go about getting this on my i pad? i can't seen to find a way. On my i phone i would go into settings and it would tell me i needed an update and then do it automatically, however it does not do this on the i pad! Please can anyone help?